8 ms·

Tesla Model 3 Falls Short of a CR Recommendation

51 points by whatok 8y ago

DmenshunlAnlsis 8y ago
The Tesla’s stopping distance of 152 feet from 60 mph was far worse than any contemporary car we’ve tested and about 7 feet longer than the stopping distance of a Ford F-150 full-sized pickup. That’s worrying, and almost as worrying is that Tesla says their braking is much faster. I’m sure plenty of fans will make comments about shorting stock, but this is Consumer Reports, and they have a very good reputation to protect. I’m not thrilled by this tidbit either. The Model 3’s stiff ride, unsupportive rear seat and excessive wind noise at highway speeds also hurt its road-test score. In the compact luxury sedan class, most competitors deliver a more comfortable ride and rear seat.
- tshannon 8y ago
  This part really intrigued me about the stopping distance: The Tesla spokeswoman says the company has the ability to update its vehicles over the air. “Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance,” she says. I'm curious the mechanism that makes that possible, or if it's just BS.
  - Cthulhu_ 8y ago
    Why would you think it's BS? The Model S gets over-the-air updates all the time; if I recall correctly, they increased the ride height a while ago through an update after a car drove over a metal wotsit, causing a puncture in the battery compartiment and a fire. They can probably update the settings for the brakes as well, as long as the underlying mechanicals support it.
    - tw04 8y ago
      There are plenty of reasons why you would default to a lower ride height. What would be the purpose of intentionally making your brakes worse than an f150?
      - gnode 8y ago
        I don't think anyone's suggesting it was intentional. Parameters for managing the brakes may just have been set badly, or the anti-locking algorithm written poorly. A possible explanation is they may have optimised it to improve handling while braking.
    - blacksmith_tb 8y ago
      I think the implicit question is "can an OTA somehow improve braking performance - why isn't it optimal already?" not "do Tesla OTAs change other aspects of the car?"
      - Nasrudith 8y ago
        Electric motors and generators are essentially the same thing run in different directions. Run electricity through a motor and it generates motion while putting load on the power. Move a generator and it creates resistance as it extracts electricity. This also answers both how they can change it and why it is not already optimal. Actively using the motors to break causes it to use energy instead of recovering it. Hybrid drivers have long known to break gradually when possible to maximize battery recharge. It is possible they had an electric neophyte as a test driver. Fair enough if they were supposed to test from the perspective of someone new to hybrids and electric cars trying a Tesla as their first.
        mshook 8y ago
        Not sure if you read the article but what they were testing is pretty much emergency braking from 60mph to full stop. So the goal is not regenerate the battery (and it doesn't matter if the driver was "an electric neophyte"), it's to brake hard and to repeat the process a couple of times to see if you get brake fade. From the article: Our testers get a car up to 60 mph, then slam on the brakes until the car comes to a stop. They repeat this multiple times to ensure consistent results. Between each test, the vehicle is driven approximately a mile to cool the brakes and make sure they don’t overheat.
        Nasrudith 8y ago
        Whoops. My mistake for giving into the temptation to segue after my explanation of what I did know.
        detaro 8y ago
        What does "gradually braking to optimize battery recharge" have to do with an emergency stop?
    - tshannon 8y ago
      I never said I thought it was BS. I was curious what the physical mechanism to change the braking characteristics was. If there was no physical mechanism that I assume it's BS.
      - onesun 8y ago
        The car most definitely has software controlled anti-lock braking equipment, and likely has software controlled electric brake cylinders. Both of those things could plausibly be updated via an OTA update.
  - deleted 8y ago
    [deleted]
  - kbd 8y ago
    They improved acceleration via a software update[1] so it's plausible at least. [1] https://www.engadget.com/2016/11/16/tesla-p100d-software-performance-upgrade/ https://www.engadget.com/2016/11/16/tesla-p100d-software-per... Edit: why downvotes?
  - ensignavenger 8y ago
    To me, it is disturbing. I get used to the way my vehicle handles, for it to suddenly change because of a software update could potentially be dangerous- but would almost certainly result in a trip to the mechanic for a checkup. Maybe they have a system for warning owners about these sorts of updates?
    - audionemesis 8y ago
      Well, yes. You get prompted to update your car (you can choose not to). And then after the update is complete, you get a Whats Changed prompt the next time you're in your car. Essentially a patch notes for your vehicle
      - whatok 8y ago
        For something as major as changing the way a car breaks, do you think "patch notes" (if read at all) are able to properly convey the magnitude of the change?
        greglindahl 8y ago
        How do you know that the change is driver-visible? The change might only be for braking hard enough that the anti-lock feature kicks in... which most drivers don't do very often.
        audionemesis 8y ago
        Yes? My 75D had an entire second shaved off of its 0 - 60 time. I was aware of the change and was able to deal with it just fine... I'm also not sure what the alternative you're imagining here is. Take it in to a shop just to have them install the update for you? I also don't see how this is any different than changing worn out brakes on an old ICE car. I had the brakes changed in my old '97 Accord, and the difference was noticeable when I pulled it out of the driveway. I think you need to give people a little more credit... Also, the Whats Changed prompt literally takes up the entire 17in touch screen. It's sort of hard to miss.
  - gnode 8y ago
    My understanding is that car brakes can generally exert more braking force than the tire's grip on the road. A long stopping distance may represent a problem with the anti-lock braking system (which is likely software controlled, and can be updated over the air).
    - Animats 8y ago
      Interestingly, Waymo's self-driving car cannot be updated remotely.[1] As a security measure, Waymo deliberately did not install a data connection to allow that. Probably a good decision. [1] http://www.documentcloud.org/documents/4458000-Waymo-Driverless-AV-Application.html http://www.documentcloud.org/documents/4458000-Waymo-Driverl...
      - gnode 8y ago
        That's probably also to do with Waymo's cars being developed primarily for ride hailing fleets. With a private ownership model, requiring owners of variable technological faculty to manually apply updates would be less practical.
      - londons_explore 8y ago
        That was more a PR move than a real security measure. Signing updates and checking signatures is established technology to certify that updates come from the right place and are not tampered with. That and the updates are likely >10 GB, so you wouldn't want to download them over mobile data anyway.
    - magduf 8y ago
      It could, but it could also be a function of the car's weight (batteries are heavy) and the tires it comes equipped with from the factory. Poor tires will yield poor braking performance due to lack of grip.
      - dragontamer 8y ago
        But it can't be poor tires, because the Model 3's brakes were proper in the first test (~130 feet stopping distance). The same car with the same tires then had different braking behavior in every test after the first test. That's just odd.
- abritinthebay 8y ago
  "this is Consumer Reports, and they have a very good reputation to protect" CR doesn't have a very good reputation though? I mean... they used to. But their reputation is middling at best now.
  - brianwawok 8y ago
    Who has better reviews for consumer goods?
- JKCalhoun 8y ago
  I understand Teslas are fairly heavy cars. That explains most of the problem I think.
  - audionemesis 8y ago
    The Model S is in fact about as heavy as a Ford F150. However, if this braking result is consistent across all Model 3 vehicles, that's a bit worrisome. I'm also a little concerned with the other issues they had (ergonomics, wind noise, etc). From everyone I know that drives or has driven a Model 3, they've had amazing experiences as far as actual driving
- ataturk 8y ago
  I would not short TSLA no matter what. It is very difficult to short a stock and win. Possibly buy long expiration put options "lotto tickets" because there are so many ways Musk can game this and win for a lot longer than you imagine.
gldalmaso 8y ago
> past driving behavior that may have affected the brake system Could this mean that such a vehicle under test would brake differently than the average driver. Since the brake is constantly being slammed during repeated tests, the software adjusts breaking parameters? Still find it odd to implement such a system, but could explain the inconsistent results.
- londons_explore 8y ago
  Since they did more tests the following day and didn't see improved performance, it doesn't seem likely related to thermal limiting in software. If I were to guess, it would be that in a sudden stop, something inside the brake mechanism heats up so much it bends or deforms, and then doesn't work so well after that. If my guess is correct, it could be an expensive recall...
  - cc439 8y ago
    I can almost guarantee the brake pads glazed over due to overheating. The pad's surface will begin to work harden once a certain temperature threshold is exceeded and that hardened surface has a much lower coefficient of friction than the original unhardened pad. This work hardened material will never return to normal so full braking performance will not be restored until it is ground away by further use of the brakes (light use, you don't overheat them again and make the problem worse). That explains why the poor braking performance was unaffected by an overnight cooldown. All that said, if the Model 3 is glazing brake pads with a single emergency stop then they need to issue a recall and figure out a fix.
    - sliken 8y ago
      The whole brake from 60-0 10 times quickly seems like a stupid metric. Would you rather have shorter stop times, but a design that fails at 15 times? Or a brake that adapts to that load and progressively stops more gently. Any sane driver would adjust. Seems pretty stupid to evaluate cars on such a weird metric. Sure 60 to 0 or 80 to zero, but what sane person is going to accelerate up to speed as quickly as possible and try again. Maybe Tesla's doing so poorly because it gets back to 60 quicker than it's competition.
zippzom 8y ago
Seems like a terrible design choice to make lots of basic adjustments use the touch screen. Adjusting the mirror and AC vents with a touch screen is almost guaranteed to be a terrible experience, especially since people do those often while they're driving.
- craftyguy 8y ago
  You frequently adjust your mirror when driving? That's something I do once in a few months (if that), twice if someone drives my car and adjusts the mirrors to fit them.. Perhaps you should adjust your seat instead?
  - dragontamer 8y ago
    Mirrors? No. Air conditioning? Yes. On longer drives, the positioning of the sun greatly determines whether or not my AC is running. Radio stations also are frequently changed, as is volume. If someone is talking to me in the passenger's seat, I instinctively turn down the volume of the radio for example. I personally prefer physical buttons for these various tasks. Physical buttons are always there. I don't have to look at the screen to ensure that I'm on the "correct app" or whatever before trying to fiddle with the AC or volume.
  - timeisapear 8y ago
    Living in a city, I must manually retract side mirrors when parking on small streets and extend them before driving. Often need to readjust the mirrors each time after extending them.
    - greglindahl 8y ago
      I take it that you don't drive a car that folds its mirrors when you put it in Park, which is now a common feature.
  - kalleboo 8y ago
    I share a car with my wife, who is much shorter than I am, so yes
RickJWagner 8y ago
I love cars, all kinds of cars. I bought my son a Prius, I even enjoy driving that (just for the unusual driving experience.) I like to see how long I can go on just electric power. But I'm starting to have real doubts about Tesla. Elon talks a great game, but they've had setback after setback after setback. I have to wonder what the long-term ownership experience will be like. Good luck to Tesla. I'd love to see them turn out well.
mdekkers 8y ago
Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance, I'm sorry, but that is complete bullshit. Emergency braking isn't "a corner case", it is one of the primary use-cases of a braking system. Such a statement shows a blatant disregard for the intelligence of their customers, it is shocking.

51 points by whatok 8y ago

The Tesla’s stopping distance of 152 feet from 60 mph was far worse than any contemporary car we’ve tested and about 7 feet longer than the stopping distance of a Ford F-150 full-sized pickup. That’s worrying, and almost as worrying is that Tesla says their braking is much faster. I’m sure plenty of fans will make comments about shorting stock, but this is Consumer Reports, and they have a very good reputation to protect. I’m not thrilled by this tidbit either. The Model 3’s stiff ride, unsupportive rear seat and excessive wind noise at highway speeds also hurt its road-test score. In the compact luxury sedan class, most competitors deliver a more comfortable ride and rear seat.

tshannon 8y ago
This part really intrigued me about the stopping distance: The Tesla spokeswoman says the company has the ability to update its vehicles over the air. “Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance,” she says. I'm curious the mechanism that makes that possible, or if it's just BS.
- Cthulhu_ 8y ago
  Why would you think it's BS? The Model S gets over-the-air updates all the time; if I recall correctly, they increased the ride height a while ago through an update after a car drove over a metal wotsit, causing a puncture in the battery compartiment and a fire. They can probably update the settings for the brakes as well, as long as the underlying mechanicals support it.
  - tw04 8y ago
    There are plenty of reasons why you would default to a lower ride height. What would be the purpose of intentionally making your brakes worse than an f150?
    - gnode 8y ago
      I don't think anyone's suggesting it was intentional. Parameters for managing the brakes may just have been set badly, or the anti-locking algorithm written poorly. A possible explanation is they may have optimised it to improve handling while braking.
  - blacksmith_tb 8y ago
    I think the implicit question is "can an OTA somehow improve braking performance - why isn't it optimal already?" not "do Tesla OTAs change other aspects of the car?"
    - Nasrudith 8y ago
      Electric motors and generators are essentially the same thing run in different directions. Run electricity through a motor and it generates motion while putting load on the power. Move a generator and it creates resistance as it extracts electricity. This also answers both how they can change it and why it is not already optimal. Actively using the motors to break causes it to use energy instead of recovering it. Hybrid drivers have long known to break gradually when possible to maximize battery recharge. It is possible they had an electric neophyte as a test driver. Fair enough if they were supposed to test from the perspective of someone new to hybrids and electric cars trying a Tesla as their first.
      - mshook 8y ago
        Not sure if you read the article but what they were testing is pretty much emergency braking from 60mph to full stop. So the goal is not regenerate the battery (and it doesn't matter if the driver was "an electric neophyte"), it's to brake hard and to repeat the process a couple of times to see if you get brake fade. From the article: Our testers get a car up to 60 mph, then slam on the brakes until the car comes to a stop. They repeat this multiple times to ensure consistent results. Between each test, the vehicle is driven approximately a mile to cool the brakes and make sure they don’t overheat.
        Nasrudith 8y ago
        Whoops. My mistake for giving into the temptation to segue after my explanation of what I did know.
      - detaro 8y ago
        What does "gradually braking to optimize battery recharge" have to do with an emergency stop?
  - tshannon 8y ago
    I never said I thought it was BS. I was curious what the physical mechanism to change the braking characteristics was. If there was no physical mechanism that I assume it's BS.
    - onesun 8y ago
      The car most definitely has software controlled anti-lock braking equipment, and likely has software controlled electric brake cylinders. Both of those things could plausibly be updated via an OTA update.
- deleted 8y ago
  [deleted]
- kbd 8y ago
  They improved acceleration via a software update[1] so it's plausible at least. [1] https://www.engadget.com/2016/11/16/tesla-p100d-software-performance-upgrade/ https://www.engadget.com/2016/11/16/tesla-p100d-software-per... Edit: why downvotes?
- ensignavenger 8y ago
  To me, it is disturbing. I get used to the way my vehicle handles, for it to suddenly change because of a software update could potentially be dangerous- but would almost certainly result in a trip to the mechanic for a checkup. Maybe they have a system for warning owners about these sorts of updates?
  - audionemesis 8y ago
    Well, yes. You get prompted to update your car (you can choose not to). And then after the update is complete, you get a Whats Changed prompt the next time you're in your car. Essentially a patch notes for your vehicle
    - whatok 8y ago
      For something as major as changing the way a car breaks, do you think "patch notes" (if read at all) are able to properly convey the magnitude of the change?
      - greglindahl 8y ago
        How do you know that the change is driver-visible? The change might only be for braking hard enough that the anti-lock feature kicks in... which most drivers don't do very often.
      - audionemesis 8y ago
        Yes? My 75D had an entire second shaved off of its 0 - 60 time. I was aware of the change and was able to deal with it just fine... I'm also not sure what the alternative you're imagining here is. Take it in to a shop just to have them install the update for you? I also don't see how this is any different than changing worn out brakes on an old ICE car. I had the brakes changed in my old '97 Accord, and the difference was noticeable when I pulled it out of the driveway. I think you need to give people a little more credit... Also, the Whats Changed prompt literally takes up the entire 17in touch screen. It's sort of hard to miss.
- gnode 8y ago
  My understanding is that car brakes can generally exert more braking force than the tire's grip on the road. A long stopping distance may represent a problem with the anti-lock braking system (which is likely software controlled, and can be updated over the air).
  - Animats 8y ago
    Interestingly, Waymo's self-driving car cannot be updated remotely.[1] As a security measure, Waymo deliberately did not install a data connection to allow that. Probably a good decision. [1] http://www.documentcloud.org/documents/4458000-Waymo-Driverless-AV-Application.html http://www.documentcloud.org/documents/4458000-Waymo-Driverl...
    - gnode 8y ago
      That's probably also to do with Waymo's cars being developed primarily for ride hailing fleets. With a private ownership model, requiring owners of variable technological faculty to manually apply updates would be less practical.
    - londons_explore 8y ago
      That was more a PR move than a real security measure. Signing updates and checking signatures is established technology to certify that updates come from the right place and are not tampered with. That and the updates are likely >10 GB, so you wouldn't want to download them over mobile data anyway.
  - magduf 8y ago
    It could, but it could also be a function of the car's weight (batteries are heavy) and the tires it comes equipped with from the factory. Poor tires will yield poor braking performance due to lack of grip.
    - dragontamer 8y ago
      But it can't be poor tires, because the Model 3's brakes were proper in the first test (~130 feet stopping distance). The same car with the same tires then had different braking behavior in every test after the first test. That's just odd.
abritinthebay 8y ago
"this is Consumer Reports, and they have a very good reputation to protect" CR doesn't have a very good reputation though? I mean... they used to. But their reputation is middling at best now.
- brianwawok 8y ago
  Who has better reviews for consumer goods?
JKCalhoun 8y ago
I understand Teslas are fairly heavy cars. That explains most of the problem I think.
- audionemesis 8y ago
  The Model S is in fact about as heavy as a Ford F150. However, if this braking result is consistent across all Model 3 vehicles, that's a bit worrisome. I'm also a little concerned with the other issues they had (ergonomics, wind noise, etc). From everyone I know that drives or has driven a Model 3, they've had amazing experiences as far as actual driving
ataturk 8y ago
I would not short TSLA no matter what. It is very difficult to short a stock and win. Possibly buy long expiration put options "lotto tickets" because there are so many ways Musk can game this and win for a lot longer than you imagine.

gldalmaso 8y ago

> past driving behavior that may have affected the brake system Could this mean that such a vehicle under test would brake differently than the average driver. Since the brake is constantly being slammed during repeated tests, the software adjusts breaking parameters? Still find it odd to implement such a system, but could explain the inconsistent results.

londons_explore 8y ago
Since they did more tests the following day and didn't see improved performance, it doesn't seem likely related to thermal limiting in software. If I were to guess, it would be that in a sudden stop, something inside the brake mechanism heats up so much it bends or deforms, and then doesn't work so well after that. If my guess is correct, it could be an expensive recall...
- cc439 8y ago
  I can almost guarantee the brake pads glazed over due to overheating. The pad's surface will begin to work harden once a certain temperature threshold is exceeded and that hardened surface has a much lower coefficient of friction than the original unhardened pad. This work hardened material will never return to normal so full braking performance will not be restored until it is ground away by further use of the brakes (light use, you don't overheat them again and make the problem worse). That explains why the poor braking performance was unaffected by an overnight cooldown. All that said, if the Model 3 is glazing brake pads with a single emergency stop then they need to issue a recall and figure out a fix.
  - sliken 8y ago
    The whole brake from 60-0 10 times quickly seems like a stupid metric. Would you rather have shorter stop times, but a design that fails at 15 times? Or a brake that adapts to that load and progressively stops more gently. Any sane driver would adjust. Seems pretty stupid to evaluate cars on such a weird metric. Sure 60 to 0 or 80 to zero, but what sane person is going to accelerate up to speed as quickly as possible and try again. Maybe Tesla's doing so poorly because it gets back to 60 quicker than it's competition.

zippzom 8y ago

Seems like a terrible design choice to make lots of basic adjustments use the touch screen. Adjusting the mirror and AC vents with a touch screen is almost guaranteed to be a terrible experience, especially since people do those often while they're driving.

craftyguy 8y ago
You frequently adjust your mirror when driving? That's something I do once in a few months (if that), twice if someone drives my car and adjusts the mirrors to fit them.. Perhaps you should adjust your seat instead?
- dragontamer 8y ago
  Mirrors? No. Air conditioning? Yes. On longer drives, the positioning of the sun greatly determines whether or not my AC is running. Radio stations also are frequently changed, as is volume. If someone is talking to me in the passenger's seat, I instinctively turn down the volume of the radio for example. I personally prefer physical buttons for these various tasks. Physical buttons are always there. I don't have to look at the screen to ensure that I'm on the "correct app" or whatever before trying to fiddle with the AC or volume.
- timeisapear 8y ago
  Living in a city, I must manually retract side mirrors when parking on small streets and extend them before driving. Often need to readjust the mirrors each time after extending them.
  - greglindahl 8y ago
    I take it that you don't drive a car that folds its mirrors when you put it in Park, which is now a common feature.
- kalleboo 8y ago
  I share a car with my wife, who is much shorter than I am, so yes

RickJWagner 8y ago

I love cars, all kinds of cars. I bought my son a Prius, I even enjoy driving that (just for the unusual driving experience.) I like to see how long I can go on just electric power. But I'm starting to have real doubts about Tesla. Elon talks a great game, but they've had setback after setback after setback. I have to wonder what the long-term ownership experience will be like. Good luck to Tesla. I'd love to see them turn out well.

mdekkers 8y ago

Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance, I'm sorry, but that is complete bullshit. Emergency braking isn't "a corner case", it is one of the primary use-cases of a braking system. Such a statement shows a blatant disregard for the intelligence of their customers, it is shocking.